The latest on what's still a problem, what's getting fixed, and what's been taken care of, direct from the Blogger team.
Tuesday, September 26, 2006
If a user has a Google Account but hasn’t signed up for Blogger with it, and they get invited to a blog, they may not be able to post to it. The fix for this is to go to beta.blogger.com and explicitly sign up for Blogger from there. Update (9/26): This has been fixed. The workaround is no longer necessary; new authors will be prompted to sign up for Blogger when they accept the invitation.